Effects Of Thinning Disturbance On Carbon Storage And Carbon Balance In Coniferous And Broad-leaved Mixed Forest In Jiaohe,Jilin Province

As an important management measure for forest cultivation,harvesting will affect forest growth,vegetation renewal,spatial structure,species diversity and other aspects.At the same time,it will also have an important impact on forest ecosystem biomass,carbon storage,and carbon balance.Coniferous and broad-leaved mixed forests,as one of the most important forest types in the northeastern forest region,have a wide distribution and large area.Researching the impact of logging on their carbon stocks and carbon balance will play an important role in studying the carbon balance of forest ecosystems in China and even in the world.The key role is to provide basic data for exploring human disturbances and the impact of business processes on the carbon cycle of forest ecosystems.In this study,4 different cutting intensity plots and plots at different recovery stages were used as research objects to construct biomass equations for 12 arbor species and 20 shrub species in the study area,combined with post-harvest survey data for 2011 and 2015,and 2010 The two survey data of different recovery stages in year 2015 and year 2015 estimated the biomass,carbon storage and carbon fixed amount of each component of different harvesting intensity and different development stages;meanwhile,the soil respiration in the plot was measured and calculated using LI-cor 8100.CO2 annual carbon emission,according to the CO2 annual carbon fixed amount and the difference between the release of the assessment of the different areas of the study area intensities and recovery stage of the forest ecosystem carbon source/sink capacity.The results and conclusions are as follows:(1)The biomass optimization models of the 12 tree species all had high explanatory power and the explanatory power was more than 90%.The biomass of each component could be well estimated.The proportions of biomass allocation of the 12 tree species were the highest,accounting for 50%,followed by branches and stems,accounting for about 20%each,and the lowest leaf biomass,generally less than 10%.The biomass optimization model for each of the 20 shrubbery species also has good explanatory power.The proportions of biomass allocation for each tree species show that the ratios of stem,branch and root allocation are roughly equal,all account for about 30%,and leaf biomass accounts for about 10%.(2)The order of biomass of tree layers in the harvesting intensity and development stage was dry(about 50%)>branch(about 25%)>root(about 23%)>foliage(about 2%).With the increase of thinning intensity,the total biomass of the vegetation layer gradually decreased,and the total biomass of the harvested vegetation layers at LT,MT and HT were 195.73,170.82 and 118.94 t·ha-1,respectively.The total biomass of vegetation layers at different development stages.The order was:MF(313.61 t·ha-1)>OGF(271.63 t·ha-1)>MF(199.31 t·ha-1)>NMF(196.71 t·ha-1).(3)The carbon stocks of forest ecosystems in different sampling intensity regions gradually decreased with increasing thinning intensity.The ecosystems carbon stocks of the CK,LT,MT,and HT were 457.184,420.299,357.224,and 360.292 t-C ha-1.The order of carbon storage of the components of the thinning plot ecosystem is roughly as follows:soil layer>tree layer>litter layer>withered layer>herb layer>shrub layer.The total carbon storage of forest ecosystems at each development stage gradually increased with the development stage.The total carbon storage in HF,NMF,MFand OGF was 472.518,514.710,592.129 and 638.445 t-C-ha-1,respectively..The highest proportion of soil layers in the carbon stocks of various sampling sites and development stages is as high as 75%-85%,while the entire vegetation layer carbon reserves only account for 15%-25%,and the tree layer accounts for above 80%in the vegetation layer..(4)The total soil respiration varied with different harvesting intensity.The total soil respiration rates of CK,LT,MT,and HT were 3.449,4.053,4.123 and 3.361 ?mol·m-2·s-1,respectively.HF,NMF,MF and OGF were 2.659,3.247,2.858 and 4.322?mol·m-2·s-1,respectively.OGF was significantly higher than the other three stages,with no significant difference among the other three development stages(p<0.05).Root respiration showed the same pattern.From the perspective of the distribution ratio of soil components,all treatments showed the highest proportion of root respiration(41.31-45.78%),followed by heterotrophic respiration(32.05-34.46%),and lowest litter respiration(22.17-24.64%),the distribution ratio of the same component between the treatments was not much different,and cutting did not change the distribution ratio of soil respiration rate of each component.(5)The NEPs of forest ecosystems with different harvesting intensities were all positive,and all four plots showed carbon sink function.After the harvesting,the NEPs of the forest ecosystems were all increased.Moderate harvesting,intensity harvesting,and light harvesting were increased by 122.8,104.5,and 76.5%,respectively,compared to the control treatments;NEPs also showed carbon sink function at different stages of development,and their order was MF(2.1 56 t·C·ha-1·a-1)>HF(1.994 t·C·ha-1·a-1)NMF(1.759 t·C·ha-1·a-1)>OGF(1.604 t·C·ha-1·a-1).